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Surface Renewal: An Advanced Micrometeorological Method for Measuring and Processing Field-Scale Energy Flux Density Data
Published on: December 12, 2013
Erythemal dose rate under noon overcast skies
1Instituto de Estudos Avançados, Rod. dos Tamoios km 5.5, Torrão de Ouro II, São José dos Campos, SP CEP 12228-001, Brazil. abel@ieav.cta.br
Summary
Overcast skies in tropical urban areas can lead to high ultraviolet radiation (UVR) exposure, with some events reaching extreme levels. Understanding these UVR levels is crucial for public health and sun safety awareness.
Area of Science:
- Environmental science
- Atmospheric physics
- Dermatology
Background:
- Overcast skies can lead to increased outdoor activity, potentially increasing exposure to ultraviolet radiation (UVR).
- Assessing UVR levels under overcast conditions is important for understanding real-world sun exposure risks.
Purpose of the Study:
- To investigate the incidence and characteristics of UVR under noon overcast skies in an urban, tropical environment.
- To quantify erythemal dose rates (EDR) and identify factors influencing extreme UVR events.
Main Methods:
- Monitoring of UVR under noon overcast skies at an urban, tropical site.
- Analysis of erythemal dose rates (EDR) and calculation of Standard Erythema Dose (SED).
- Identification of cloud genera associated with different UVR levels and enhancement events.
Main Results:
- 153 instances of noon overcast skies recorded, with EDRs reaching up to 0.395 W m(-2) (Extreme UV-Index).
- Average EDR was 0.121 W m(-2) (Moderate UVI), with erythemal doses averaging 7.7 SED.
- 34% of extreme UVI events showed radiation enhancement up to 19% above summer peak values, lasting an average of 4.5 minutes.
- Cloud types like Cumulus and Altostratus were predominant during high UVR events.
Conclusions:
- Overcast conditions in tropical urban areas can pose significant UVR risks, including extreme levels and radiation enhancement events.
- Specific cloud types influence UVR intensity, with Altostratus and Cirrus clouds potentially increasing radiation enhancement.
- Findings highlight the need for continued UVR monitoring and public awareness, even under seemingly overcast skies.
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